Abnormal C5-bound N-heterocyclic carbenes: Extremely strong electron donor ligands and their iridium(I) and iridium(III) complexes

被引：274

作者：

Chianese, AR ^{[1
]}

Kovacevic, A ^{[1
]}

Zeglis, BM ^{[1
]}

Faller, JW ^{[1
]}

Crabtree, RH ^{[1
]}

机构：

[1] Yale Univ, Dept Chem, New Haven, CT 06520 USA

来源：

ORGANOMETALLICS | 2004年 / 23卷 / 10期

关键词：

D O I：

10.1021/om049903h

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

Imidazolium salts are found to bind abnormally via C5 to iridium(I) and iridium(III) to give air-stable monodentate N-heterocyclic carbene complexes. Abnormal ligand binding was verified by X-ray diffraction in both Ir(I) and Ir(III) complexes. In the case of Ir(l), it is necessary to block the C2 and C4 positions to form a stable sterically protected C5-bound complex. Infrared spectroscopy on carbonyl derivatives indicates that abnormally bound N-heterocyclic carbenes are much stronger electron donors than their ubiquitous C2-bound counterparts. The Tolman electronic parameter for 1-isopropyl-2,4-diphenyl-3-methylimidazolin-5-ylidene is 2039 cm(-1), compared to ca. 2050 cm(-1) for typical NHCs.

引用

页码：2461 / 2468

页数：8

共 59 条

[1] Chelated iridium(III) bis-carbene complexes as air-stable catalysts for transfer hydrogenation [J].